2011 Young Medal and Prize

Professor Ian A Walmsley

University of Oxford

For his innovative contributions to optical physics and technology, in particular in the areas of quantum control, quantum optics and ultra-fast metrology.

Ian Walmsley is a pioneer in Quantum Optics, using lasers to engineer photons with precisely controlled quantum states, which, in concert with the control of the quantum states of atoms or molecules provide the basis of the emerging Quantum Technologies of the 21st century such as Quantum Computing.

A unique feature of quantum systems is ‘entanglement’ – where the quantum states of two (or more) particles or photons are correlated beyond what is possible in classical physics. Ian Walmsley pioneered the production of entangled photon pairs using ultra-short laser pulses in non-linear waveguides using parametric down conversion, a process that ‘splits’ one photon into two. His group developed the first general methods for engineering space-time entanglement and his sources provide the purest single photon states yet produced. These developments were enabled by his invention of self-referencing spectral interferometry – a device for measuring spectral amplitude and phase and so fully characterising pulses of light. He holds the patent on the SPIDER instrument based on this concept that is now commercialized and widely used to measure ultra-short laser pulses down to attosecond durations.

He has also pioneered approaches to complete measurement of quantum systems that underpin these new technologies. He was first to demonstrate Quantum State Tomography (QST) in matter, and to use this to characterise squeezed vibrational states of molecules using methods of coherent control and ultra-fast dynamical spectroscopy. QST enables reconstruction of the parameters needed to specify a quantum state. His group invented a photon-number resolving detector allowing the first demonstration of quantum detector tomography, QDT. Together with Quantum Process Tomography, QST and QDT are key elements for verification of quantum information processing systems.

Ian Walmsley’s leadership has produced key advances in practical and theoretical Quantum Optics and placed the UK at the forefront of this exciting field.